On arrival at OR, standard perioperative monitoring will be established, including an Auditory Evoked Potential (AEP) monitor for anaesthetic depth measurements (AEP Monitor/2, Danmeter, Odense, Denmark) and radial arterial and central venous lines. General anaesthesia is induced with propofol 0.5-1 mg/kg and fentanyl 10 μg/kg. Tracheal intubation will be facilitated using atracurium 0,5 mg/kg. Sevoflurane is used to maintain an anaesthetic depth adjusted to an AAI index of 15-30 as recorded by the AEP monitor. Hemodynamic stability will be obtained by the use of colloidal solution administration, guided by the use of intra-operative transesophageal echocardiography, and norephineprine to maintain a mean arterial pressure above 75 mmHg-Also during CPB. A lumbar puncture will be repeated the first postoperative day repeating the measurement of markers in CSF A certified cardiologist or anaesthesiologist assess focal neurological impairment before and within 24 hours after the procedure.